Its good to be cautious before you eat something, but you can also use it as a good opportunity to learn more about your ecosystem. Find a copy of a good book like Steve Brill or Samuel Thayer. Read through it, remember what the plants look like (both written description and picture) and what habitats they are found. When you are walking through the woods, just observe. You would be amazed at how much you will start to learn and remember just by observing. You learn a lot more about your local park when you start deliberately seeing more.
I would recommend consulting with your local foraging expert before eating anything. There are many reasons why you may not want to eat a particular plant- it could be "edible" but in a highly sprayed area. There are many local botany clubs and mycology clubs that are probably in your area. Lot of great knowledge from those types of folks.